So I tried and failed to working out twice a day splitting up weights and cardio so now I am combining them all in one. I wear a heart monitor during the entire workout. Start out at 120-130 bpm for 15 min as a warmup on the stairs and finish with the cardio after weights for 25 min. The first 15 min of the post weights cardio my heart rate is at 145-160 bpm and the final 10 min it's at 125-140 bpm. Is this okay to do if I want to maintain my muscle and burn fat? I'm 24, 275lbs 18 percent bf.